Dyeing protein fibers with chbom



Patented Aug. 22, 1950 was DYEING PROTEIN FIBERS WITH CHROM- ABLE ANTHRAQUIN-ONE 'COLORS BY THE METACHROME PROCESS Willard H. Watkins, Bound Brook, Henry E. Millson, Plainfield, and Chester A. Amick, Bound Brook, N. J., assignors to American 'Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing.

Application July 18, 1947,

Serial No. 761,982

14 Claims. 1

This invention relates to improvements in the metachrom dyeing process with chromable anthraquinone colors.

In the past, fibers such as Wool, silk, synthetic protein fibers of similar type from casein, and the like have been dyed by the metachrome process in which the dyestuii and a mordant containing a chromium compound have been present in the dye-bath. In the dyeing procedure the dye is affixed to the fiber and is metallized. There have been many disadvantages to the metachrome dyeing process. For one thing, dye penetration has sometimes been inadequate because of premature reaction with the chromium containing mordant.

Thus which do not penetrate all of the fibers or are destroyed during the dyeing operation, particularly in the case of heavy shades, have been considered unsuitable for use in the metachrome process and have required resort to a process starting out with the preformed metallized dye or with a top or bottom chrome process. Among the chromable dyes which have been considered unsuitable for dyeing by the metachrome process are the chromable anthraquinone dyes and these dyes have, therefore, been excluded hitherto from metachrome dyeing.

Numerous attempts have been made to increase the penetration of the dyes and obtain stronger dyeings. One of the earlier attempts involved the use of cationic surface active agents. This 0 process, however, did not achieve practical success because although greatly increased penetration resulted there was reaction between the surface active agent and the colored constituents of the dye-bath to produce a colored scum of precipitated dye and does. These larger colored aggregates often caused serious spots or fiocs in the dyeing and precluded the practical use of this method. The next development which was practically useful involved the addition to the meta- 0 chrome dye-bath of both cationic and nonionic surface active agents, the latter serving to keep the reaction products of the cationic agent and colored constituents in fine dispersion. This process forms the subject matter of the application of Millson and Royer, Serial No. 420,504, filed November 26, 1941, now abandoned.

It was later found 'by Boyer and Amick (application Serial No. 542,445, filed June 27, 1944 now Patent No. 2,434,178) that if the cationic In the earlier application Ser. No. 750,886, filed May 27, 1947, we have described and claimed a metachrome process in which the colloidized cationic surface active agent is associated with the other features. The first is the presence of a salt of an alkaline earth metal such as magnesium sulfate and secondly a procedure in which the dye bath initially has a pH sufiiciently high so that rapid chromation is prevented or retarded and the pH is then progressively lowered by boiling until final chromation results.

According to the present invention we have found that with certain chromable anthraquinone colors a marked increase in color strength is obtained if the alkaline earth metal salt and initial high pH followed by a reduced pH is used without any cationic surface active agent. The alkaline earth metal salt in the present case as in the earlier application above referred to must of course have an anion which does not form complexes with chromium containing salts. The increase in strength is marked and there is no problem of scum formation. It is thus possible to obtain strengths which do not compare unfavorably with those obtained by the process of the copending application above referred to without requiring any cationic agent and hence encountering no problem of colored scum or 1100 formation.

It is not known why with chromable anthraquinone colors the marked increase in strength is obtained Without any cationic surface active agent, This is not generally true because with many chromable colors of other types the cationic surface active agent is essential. It is possible that the mechanism of dyeing the chromable anthraquinone colors by a metachrome process may differ somewhat from the dyeing mechanism of some other chromable colors and it is not desired to limit the present invention to any theory of dyeing mechanism.

The invention will be described in conjunction with the following specific examples. The parts are by weight.

Example 1 A dye bath is prepared comprising 2% of the dye having Color Index No. 1085, 10% ammonium sulfate and 1% potassium bichromate in 400 ml. of distilled water. A 5-g. woolen skein or piece, pre-wet with distilled water, is entered into the dye bath which is gradually heated to the boil in about 30 minutes. The bath is then boiled for about 30 minutes, after which the volume of water is replenished and 2% of 28% acetic acid is add- 5 ed. Boiling is continued for another 30 minutes,

the Water again replenished and 4% of 28 acetic acid is added. Boiling is again continued for about 30 minutes after which the dyed wool is removed, rinsed in distilled water, squeezed and dried. During the dyeing the wool is turned intermittently to obtain penetration of maximum uniformity. This is a control dyeing and the procedure used is one that is often recommended for dyeing chromable colors by the metachrome process. All the above percentages are based on the weight of the wool.

A second dye bath is prepared comprising 2% of the same dye, 2% ammonium hydroxide to give a pH of about 9, 10% magnesium sulfate containing 7 molecules of water of crystallization and 0.6% potassium bichromate in 400 ml. of distilled water. A -gram Wool sample is entered into this bath and dyed as above. The color value of the two samples is then determined b means of a spectrophotometer. If the value of the control is 100%, then the wool dyed in the solution containing the ammonium hydroxide and the magnesium sulfate has a value of 116% Example 2 The procedure of the preceding example is followed exactly except the dye having Color Index 1034 is used instead of the dye having Color Index 1085. When the control dyeing is given a value of 100%, then the wool dyed in the bath containing the ammonium hydroxide and the magnesium sulfate is 109%.

Example 3 The procedure of Example 1 is repeated exactly except 10% of calcium nitrate is used instead of 10% of the magnesium sulfate of Example 1. When the control dyeing is assigned a value of 100%, the skein dyed in the dyebath containin the calcium nitrate and ammonium hydroxide has a color value of 118%.

Example 4 The procedure of Example 1 is repeated exactly except 10% strontium nitrate is used instead of the magnesium sulfate of Example 1. When the control dyeing is assigned a value of 100%, the wool dyed in the presence of the strontium salt and ammonium hydroxide has a value of 116%.

We claim:

1. A method of dyeing which comprises subjecting substantially unmetallized protein fibers to the action of a dye bath formed by mixing a chromable anthraquinone dye, a soluble alkaline earth metal salt the anion of which does not form complexes with chromium containing salts, a soluble chromium containing salt, water, and sufficient alkali to make the bath alkaline and to cause said dye to react with said alkaline earth metal salt to form an alkaline earth metal complex of said dye and insufiicientto vmaterially damage said fibers, partially dyeing said fibers from said complex, gradually lowering the pH of said bath to a point where decomposition of said complex and chromation of the dye take place, and completing the dyeing at said lowered pH.

2. A method of dyeing which comprises subjecting substantially unmetallized protein fibers to the action of a dye bath formed b mixing a chromable anthraquinone dye, a soluble chromium containing salt, magnesium sulfate, water, and sufficient alkali to make the bath alkaline and to cause said dye to react with said alkaline earthv plex of said dye and insuificient to materially damage said fibers, partially dyeing said fibers from said complex, gradually lowering the pH of said bath to a point where decomposition of said complex and chromation of the dye take place, and completing the dyeing at said lowered pH.

3. A method of dyeing which comprises subjecting substantially unmetallized wool fibers t0 the action of a dye bath formed by mixing a chromable anthraquinone dye, a soluble alkaline earth metal salt the anion of which does not form complexes with chromium containing salts, a soluble chromium containing salt, Water, and sufficient alkali to make the bath alkaline and to cause said dye to react with said alkaline earth metal salt to form an alkaline earth metal complex of said dye and insufficient to materially damage said fibers, partially dyeing said fibers from said complex, gradually lowering the pH of said bath to a point where decomposition of said complex and chromation of the dye take place, and completing the dyeing at said lowered pH.

4. A method of dyeing which comprises subjecting substantially unmetallized wool fibers to the action of a dye bath formed by mixing a chromable anthraquinone dye, a soluble chromium containing salt, magnesium sulfate, water, and sufficient alkali to make the bath alkaline and to cause said dye to react with said alkaline earth metal salt to form an alkaline earth metal complex of said dye and insufiicient to materially damage said fibers, partially dyeing said fibers ,from said complex, gradually lowering the pH of 7 said bath to a point where decomposition of said complex and chromation of the dye take place, and completing the dyeing at said lowered pH.

, 5. A method of dyeing which comprises subjecting substantially unmetallized wool fibers to the action .of a dye bath formed by mixing a chromable anthraquinone dye, a soluble alkaline earth metal salt the anion of which does not form complexes with chromium containing salts, a soluble chromium containing salt, water, and sumcient alkali to make the bath alkaline, but with a pH not greater than 9.5, and to cause said dye to react with said alkaline earth metal salt to form an alkaline earth metal complex of said dye and insufficient to materially damage said fibers, partially dyeing said fibers from said complex, gradually lowering the pH of said bath to a point where decomposition of said complex and chromation of the dye take place, and completing the dyeing at said lowered pH.

6. A method of dyeing which comprises subjecting substantially unmetallized wool fibers to the action of a dye bath formed by mixing a chromable anthraquinone dye, a soluble chromium containing salt, magnesium sulfate, water, and vsufilcient alkali to make the bath alkaline, but with a pH not greater than 9.5, and to cause said dye to react with said alkaline earth metal salt to form an alkaline earth metal complex of said dye and insuificient to materially damage said fibers, partially dyeing said fibers from said complex, gradually lowering the pH of said bath to a point where decomposition of said complex and chromation of the dye take place, and completing the dyeing at said lowered pH.

7. A method according to claim 5 in which the anthraquinone dye is dye No. 1085 of the Color Index.

8. A method according to claim 5 in which the anthraquinone dye is dye No. 1034 of the Color Index.

9. A method according to claim 1 in which the pH of the dye bath is lowered by the addition of successive small portions of acid.

10. A method according to claim 2 in which the pH of the dye bath is lowered by the addition of successive small portions of acid.

11. A method according to claim 3 in which the pH of the dye bath is lowered by the additions of successive small portions of acid.

12. A method according to claim 4 in which the pH of the dye bath is lowered by the additions of successive small portions of acid.

13. A method according to claim 5 in which the pH of the dye bath is lowered by the additions of successive small portions of acid.

14. A method according to claim 6 in which the pH of the dye bath is lowered by the additions of successive small portions of acid.

WILLARD H. WATKINS. HENRY E. MILLSON. CHESTER A. AMICK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 941,399 Winslow Nov. 30, 1909 1,511,359 Onnertz Oct. 14, 1924 1,937,531 Rogers Dec. 5, 1933 2,434,178 Royer Jan. 6, 1948 OTHER REFERENCES 

1. A METHOD OF DYEING WHICH COMPRISES SUBJECTING SUBSTANTIALLY UNMETALLIZED PROTEIN FIBERS TO THE ACTION OF A DYE BATH FORMED BY MIXING A CHROMABLE ANTHRAQUINONE DYE, A SOLUBLE ALKALINE EARTH METAL SALT THE ANION OF WHICH DOES NOT FORM COMPLEXES WITH CHROMIUM CONTAINING SALTS, A SOLUBLE CHROMIUM CONTAINING SALT, WATER, AND SUFFICIENT ALKALI TO MAKE THE BATH ALKALINE AND TO CAUSE SAID DYE TO REACT WITH SAID ALKALINE EARTH METAL SALT TO FORM AN ALKALINE EARTH METAL COMPLEX OF SAID DYE AND INSUFFICIENT TO MATERIALLY DAMAGE SAID FIBERS, PARTIALLY DYEING SAID FIBERS FROM SAID COMPLEX, GRADUALLY LOWERING THE PH OF SAID BATH TO A POINT WHERE DECOMPOSITION OF SAID COMPLEX AND CHROMATION OF THE DYE TAKE PLACE, AND COMPLETING THE DYEING AT SAID LOWERED PH. 